Pre-heat oven to 180°C. Grease two, 19cm x 19cm baking tins; line with baking paper.
Place FATE mix into a mixing bowl, add margarine.
Combine food colouring and water in a jug, pour into mixing bowl.
Using hand-held electric beaters, mix well, 1min, until smooth. Divide mixture evenly between two lined tins. Bake 20min, until risen and firm to touch. Turn on to a wire rack to cool.
Place cream cheese, sugar, and butter into a mixing bowl. Using electric beaters, mix well, 2 min, until smooth.
Using a sharp bread knife, slice each cake, horizontally. You will now have four layers of cake.
Place one cake layer on a large, flat serving plate. Place approx, 1/3 cup of frosting on top and spread evenly. Top with a second cake layer and repeat; place the final cake layer on top.
Coat the top and sides of the cake with the remaining frosting.
Leftovers store well if kept in an airtight container in the refrigerator for up to 3 days.
If you prefer a round cake, use two, 21cm round cake tins, instead of the square tins in this recipe.